1. Field of the Invention
This invention relates to optics, and more particularly to obtaining an increased fluorescent emission from a sample that is being analyzed.
2. Description of the Prior Art
In one type of analysis, fluorescent emission of light is obtained from a sample of a component if a fluid in response to a transmission thereto of monochromatic light. The spectral content of the emission is determined by the composition of the component. Because the emission is determined by the composition, emission from components comprising the fluid are often collectively referred to as a signature of the fluid.
To obtain the sample, the components comprising the fluid are, for example, chromotographically separated by forcing the fluid through an absorbing column. The column is typically comprised of silica gel particles. Each of the components pass through the column at a unique velocity, thereby causing the components to pass a known location in the column with a temporal separation therebetween. An exit line from the column usually feeds a thin walled cell of an instrument for measuring light, whereby the sample is within the cell at a known time. It should be appreciated that the sample is usually small.
An exciting beam of light is transmitted through the cell to cause the fluorescent emission. The intensity of the emission radiation is in a direct relationship with the path length of the exciting beam within the sample. However, since the sample is small, the path length is short.
It should be understood that the radiation emission is radial from the cell. Because the emission is radial, the light measuring instrument may be positioned to receive light emitted along a path angularly related to the path of the exciting beam. The light measuring instrument thereby receives a portion of the emission without receiving the exciting beam. Preferably, the path of the portion of the emission and the path of the exciting beam are perpendicular to each other.
For reasons given hereinbefore, it is desirable to have apparatus that provides an increased path length of the exciting beam within the sample. Moreover, it is desirable that the angular relationship, referred to hereinbefore, be retained.